In 1996, then-President Bill Clinton signed the federal Defense of Marriage Act (DOMA), which says that no state is obligated to recognize a same-sex union from another state.

Thirty-nine states—including Iowa—adopted their own “mini-DOMAs” and enacted laws that define legal marriage as between a man and a woman. Just this spring, Iowa’s Senate Human Resources Committee approved a resolution asking Iowa senators to pass an amendment banning gay marriage outright. Lawmakers ultimately rejected the proposal.

The constitutionality of DOMA and the state laws it spawned have not been questioned up to this point, but that will most certainly change now that same-sex marriage may be legal in Massachusetts. Also sure to enter the debate is Article IV of the U.S. Constitution that requires states to honor each other’s public acts, records, and proceedings.

UI law professor Ann Estin says the most direct precedent for these technical state-to-state marriage recognition questions are cases concerning interracial marriage. After the Civil War, many states adopted statutes prohibiting interracial marriage, but differences among the states led to enormous legal conflict until the U.S. Supreme Court ruled in 1967 that it was unconstitutional for any state to prevent marriage between people of different races.

Until the Supreme Court makes a decision, it will remain unclear whether states must recognize same-sex marriages from other states, says Tim Hagle, UI associate professor of political science. “My guess is that we’ll see the first test cases very quickly,” he says. “As soon as it’s official in Massachusetts, we’re going to have a couple get married there, move home, request marriage privileges, be denied, and file a lawsuit. We’ll have to wait and see.”